Spirit-soluble color for duplicating ink



Patented Feb. 19, 1952 UNITED STATES PATENT OFFICE Benjamin F. Skiles, New Castle County, Del., as signor to E. I. ,du Pont de Nemours and Company, Wilmington, Del., acorporation ofDelaware No Drawing. Application October 12 1950, Serial No. 189,883

1 Claim. (01. 106-22) This invention relates to spirit-soluble duplicating inks for use in transfer processes such as carbon paper or typewriter ribbon intended for preparing the master copy in a hectograph duplicating process.

It is an object of this invention to provide a black coloring matter of the above type which shall possess good copying qualities, and be capable of preparation in economical manner.

A good quality hectograph ink must possess the following properties:

It must possess the desired color: in this instance, black.

It must have good exhausting qualities, which means that, say, the 100th or 500th copy taken off the master copy shall not differ in shade appreciably from the first copy.

It must possess good working qualities, which means that it should not increase unduly the viscosity of the coating through which the color is applied to the carbon paper or typewriter ribbon.

It must not be too expensive in materials employed or in the process of preparation.

The above qualifications are particularly difficult to satisfy in the case of black, inasmuch as this shade can only be produced by using a mixture of colors, and the components of the mixture do not always exhaust in use at the same rate, and do not always have the same working qualities.

In U. S. P. 2,155,862, it has been proposed to manufacture an ink for the aforegoing purpose by mixing together in the coating vehicle (castor oil) four color components, namely, crystal violet, brilliant or ethyl green, magenta and chrysoidine.

U. S. P. 2,492,163, attempted to solve the same problem by reacting together in aqueous solution chrysoidine, crystal violet and Victoria blue, the quantity of the latter two being stoichiometrically equivalent to the quantity of chrysoidine.

Now I have found that a black coloring matter of excellent qualities for the purpose hereinabove set forth may be obtained by melting together the base form of the following colors in the following proportions, namely- Parts Chrysoidine 100 Crystal violet 66 to 89 Victoria blue 39'to 50 and then adding hydrochloric acid to the melt to convert the bases into their respective hydrochlorides.

My process has the advantage over those of the prior art in that it involves a very simple procedure, avoiding filtrations or other time consuming operations. Also, it produces an excellent shade of black by using only 3 component colors, and the color exhausts at a reasonably uniform rate, avoiding excessive variations in shade as the hectograph process is continued.

Without limiting this invention, the following examples are given to illustrate my preferred mode of operation. Parts mentioned are by weight.

Example 1 Press cakes containing approximately 25% of the bases of the following colors and water were charged into a kettle and heated until a uniform melt was obtained at about C.

Parts by weight Crystal violet (C. I. No. 681) 0.773 Victoria blue (C. I. No, 729) 0.459 Chrysoidine R (C. I. No. 21) 1.000

A 30% hydrochloric acid solution was slowly added to the melt until a 1 gram sample dissolved in 50 cc. of a 50% solution of ethyl alcohol in water gave a pH of 2.8. The melt was then cast in pans and. cooled until it solidified. It was then broken up and dried in a vacuum oven at 50 C.

Incorporation of this product in a standard mineral oil-carnauba wax vehicle yielded an ink of excellent properties which when used as a coating in the preparation of hectograph carbon paper produced a master copy having a high copying power and which gave very attractive black copies of uniform shade.

By contrast, a mechanical mixture of the same dyes produced a hectograph ink of an objectionably high viscosity and which was inferior in heat stability. The master copy produced from this ink had inferior copying power and gave copies which were not uniform in shade.

Example 2 Example 1 was repeated exactly, except using chrysoidine GN (C. I. No. 20) in place of crysoidine R. The product when used to prepare a hectograph carbon paper gave a master copy which produced jet black copies of uniform shade which were superior to those obtained by mechanically mixing the same dyes.

When the proportion of crystal violet was varied between 0.66 part and 0.89 part and the proportion of Victoria blue was varied between 0.39 part and 0.53 part in either Example 1 or 2, products were obtained which had the same excellent properties as those given in these examples but they varied somewhat in shade. In all cases it was found that the pH of the product may be adjusted to between 2.8 and 4.8, by addition of HCl, without materially affecting the qualities of the product.

I claim as my invention:

A spirit-soluble, black color for duplicating inks consisting essentially of an intimate fusion-mixture of the following colors:

BENJAMIN F. SKILES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,198,422 Hochstetter Sept. 19, 1916 2,138,836 Brewer Dec. 6, 1938 r 2,424,954 Neuman July 29, 1947 FOREIGN PATENTS Number Country Date 388,878 Germany Jan. 24, 1924 

